The use of ozone in cleaning and sanitizing laundry has been utilized for quite some time. The primary reason is that ozone is generally recognized as being effective in cleaning as well as deodorizing and sanitizing laundry while also minimizing impact to the environment. With respect to commercial applications, however, ozone is generally the preferred cleaning component as it is relatively inexpensive to manufacture and quite reliable in deodorizing and sanitizing laundry.
As is well known, the application of ozone to a cleaning fluid, such as water, acts as a disinfectant as well as assists with removing dirt, debris and other contaminants from the laundry detergent so that the laundry detergent can again be effective in removing additional dirt, debris and other contaminants from the clothing or other laundry being laundered. While it is known that dissolving ozone in a liquid, such as water, will assist with improving the cleaning and sterilization efficiency of the liquid, a number of the currently available prior art systems suffer a variety of associated drawbacks. In particular, a portion of the ozone which is added to the liquid does not become completely dissolved within the water so that such ozone can not readily directly contact any substance(s) dissolved or contained within the wash water. As a result, the undissolved ozone is rapidly given off, dissipated and/or evaporated from the liquid (wash water) as soon as the liquid enters into a reservoir, e.g., contact chamber, or some other expansion chamber, for example. As a result, such undissolved ozone is not effective in cleaning and/or disinfecting the laundry and thus not all of the ozone, which is added to the liquid or water, is active or effective in achieving the desired cleaning and/or sterilization of the laundry intended by the ozonated liquid. Further, many times, some of the replacement liquid or wash water, which is added to the washing machine during one or more of the wash cycles or stages, does not contain any ozone and such unozonated liquid generally increases the duration of the cleaning, sanitization and/or disinfection time for the laundry being washed.
It is to appreciated that washing laundry can be a relatively expensive process. It utilizes costly resources—water, energy, detergents and labor—and such laundering is often required not only to clean but completely disinfect and sanitize the laundry items. While conventional detergents and soap can be effective in removing dirt, grease, grime and other contaminants, they are not always effective in killing all of the germs and bacteria contained within the laundry. It is known to enhance the disinfection capabilities of a washing machine by introducing ozone into the washing water. The ozone improves cleaning of laundry, even at relatively low or cold wash water temperatures, and also has an antibacterial effect.
Previous systems for introducing ozone have included a simple bubble system in which ozone is bubbled through water in a washing machine drum. The efficiency of dissolving ozone in the water of such apparatus is somewhat low, and the concentration of dissolved ozone in the water is consequently low thereby resulting in only a minor enhancement in the cleaning and the antibacterial effect of the ozone. There is also the disadvantage that the amount of off-gas, i.e., the ozone which is readily given off and dissipated into the surrounding environment, from the wash water both during filling and/or during operation of the washing machine, can be considerable. The ozone gas will typically collect in the area surrounding one or more sampling ports, exhaust vents or some other outlet of the washing machine and can potentially cause health and/or safety problems in the event that any person, located adjacent or within the room accommodating the washing machine(s), is exposed to a high concentration of ozone.
In order to improve the efficiency with which ozone is dissolved in the wash water, systems using venturis have been developed. Such systems attempt to forcibly dissolve ozone in the water and thereby increase the concentration of dissolved ozone within the liquid or wash water (see the results of such a system depicted by FIG. 1) as a fresh water is added to the washing machine. However, the ozone is generally not completely and thoroughly mixed and dissolved within the water, so as to maximize contact of the dissolved ozone during the washing process and such ozone tends to dissolve out of solution fairly rapidly and become gaseous shortly after being mixed with the water and supplied to the washing machine. The contact time (CT) value for systems, which incorporate a direct injection of ozone into the water, tend to be fairly low, e.g., only achieve a CT value of 0.6 or less, for example.
In an attempt to improve the amount of ozone dissolved within the water, Daniels Equipment Company developed and manufactures a diffusion system in which the ozone is directly injected into the water contained, typically within a sump of the washing machine during the wash cycle or wash stage. The results of such system are depicted in FIG. 2 attached hereto. The CT value for such direct injection systems, which directly inject ozone into the water contained within the sump, tend to be much higher, e.g., achieved a CT value of 10.0, for example, during 20 minute wash. However, as noted in the following table, such CT values are still insufficient to kill some commonly known and prevalent infectious diseases.
With respect to commercial applications, during a typical wash cycle or wash stage, a number of infectious diseases must be reliably and consistently killed in order to prevent the spread of such infectious diseases. That is, in order to ensure reliable and consistent killing of desired infectious diseases, a cumulative contact time (CT) value—i.e., standard value calculated from the concentration of the disinfectant (i.e., parts per million or ppm of the ozone) multiplied by the total time or total duration (i.e., total minutes of wash cycle) that the disinfectant (i.e., the ozone) is in contact with the infectious disease(s)—must be achieved from the beginning of the wash cycle or wash stage and the end of the final wash cycle or wash stage. It must be appreciated from the above that the CT value can vary depending on the concentration level of the ozone as well as the time that the laundry has the ability to come into contact with any dissolved ozone (or possibly undissolved ozone). Correspondingly, in the event that the necessary cumulative CT value is not achieved by the end of the final wash cycle or wash stage, the operator can not be ensured that any infectious disease(s), which may be contained within the washed laundry, is effective cleaned and/or sanitized. Table 1 below sets forth an example of common accepted CT values for various infectious diseases.
TABLE 1CT Value forPercentLogMicrobe (Bacteria or Virus)DisinfectionReductionReductionSalmonella Choleraesuis699.9999%6 logStaphylococcus Aureus2099.9999%6 log(MRSA)Pseudomonas Aeruginosa1099.9999%6 logTrichophyton Mentagrophytes199.9999%6 logListeria Monocytogenes6 99.99%4 logCampylobacter Jejuni6 99.99%4 logAspergillus Flavus10 99.99%4 logBrettanomyces Bruxellenis6 99.99%4 logEscherichia Coli1 99.999%5 logClostridium Difficile (C. Diff)4 99.999%5 logViruses3 99.999%5 logGiardia2 99.99%4 log